ON DICH.ENA RUGOSA. 47 



characters was as great a puzzle to him as it had been to me, and 

 he was unable to make out from Cooke's " Handbook" its exact 

 position, but on carefully going through the Ascomycetous Fungi 

 in Hooker's " English Flora," he found Hysterium rttgosum described 

 as " Stroma crust-like innate, brown-black, perithecia elliptic, 

 bursting through the living bark, at length running together into 

 irregular spots." This is said to be extremely common on the 

 smooth branches of birch and oak. And Mr. Berkeley, who 

 prepared this portion of the " British Flora," states also that it is 

 usually referred to the order Lichens, from which, however, 

 Messrs. Boorer and Hooker, in accordance with the views of 

 Chevalier, Wallroth, and Fries consider it extraneous. Sir James 

 Smith long since perceived its affinity with Hysterium, from which 

 it differs in the presence of a stroma, and in its being produced on 

 living bark. Eeferenceis made to " English Botany," t. 2282, and 

 on looking at the figure and description there given, as well as to 

 the works of Fries, Acharius, and others, it was evident this was 

 undoubtedly the plant we were in search of. The synonymy is 

 curious, and well exemplifies the difficulty cryptogamic botanists 

 find in clearly defining the limits of these lowly organized plants; 

 for I find that ten well-known authors describe it as a Lichen, and 

 six equally well-known place it amongst the Fungi, whilst it is 

 rejected by both our latest .authors on these plants, Mr. Cooke, 

 in his "Handbook" (1871), merely mentioning the name of 

 Dichoena rvgosa, with the remark, " I think it should be included 

 with Lichens," and the Rev. W. A. Leighton, in his " Lichen 

 Flora," published the same year, taking no notice of it whatever. — 

 Monthly Micro. Journ. 



To these remarks of Mr. Roper on a very curious, and some- 

 what anomalous plant, we may at first suggest that his observations 

 seem to strengthen the case in favour of regarding Dichcena riigosa 

 as a Lichen. Unfortunately only part of the life histoi'y of the 

 plant is given, as tbere is more than one form of fruit, one 

 of which, the stjdosporous condition which Rabenhorst calls 

 Psilospbra, is far more common than the ascigerous. There are 

 two views taken of Dichcena, each supported by some plausibility. 

 Assuming the j^resence of gonidia as a portion of the plant, its 

 Lichenoid character is incontestible. Doubting the gonidia, but 

 accepting the polymorphic fructification, its affinities are with 

 Fungi. It is because we cannot convince ourselves that the so- 

 called " gonidia " really belong to the plant, that we hesitate to 

 exclude it wholly from association with Fungi. Since the publica- 

 tion of the " Handbook" we are by no means so strongly of 

 opinion that its affinities are more with Lichens than Fungi. If 

 with the latter, then its place in a systematic arrangement would 

 undoubtedly be amongst the Hysteriacei, but most certainly not in 

 the genus Hysterium. If Mr. Roper will carefully examine the 

 plant again under various conditions, especially the other forms of 



